JPS62185496A - Separating device for luminance signal and chrominance signal - Google Patents

Abstract

PURPOSE:To correctly separate a luminance signal and a chrominance signal from a composite color television signal according to the correlation state of a picture by separating the luminance signal and the chrominance signal of a remarkable picture element by using the information signal of the picture element constituting picture element groups decided by a correlation decision means. CONSTITUTION:In the picture element information signal of a sample point, the sample points S6-S9 of the phase of the chrominance signal are the same in phase as the sample point S3 and the sample points S1, S2, S4, S5 are opposite in phase to the sample point S3. Among the picture element blocks A-D, the block having the strongest correlation is discriminated, the picture element information signal of the block is selected, and fed to a separation filter to output the luminance signal and the chrominance signal. Namely, by using subtracters 15-18 and absolute value converters 20-23, the operation is carried out. Then, the operation result is inputted to a comparator circuit 29, the smallest value is detected, a switching controls signal is outputted from the comparison circuit 29 to a switching circuit 30, and the outputted picture element information signal is inputted to the separation filter based on the picture element information signal of the sample point S3 and separated into the luminance signal and chrominance signal by performing the operation and outputted. Thus, at the time of separating the luminance signal and the chrominance signal from the composite color television signal, according to the correlation of the luminance signal and the chrominance signal on the same screen, the most suitable separation can be performed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a luminance signal/chrominance signal separation device for separating a luminance signal and a chrominance signal from a composite color television signal.

[Conventional technology]

The current composite color television signal, for example, the composite color television signal S of the NTSC system, is a color obtained by quadrature two-phase modulation of a luminance signal Y and two color difference signals U and V (or I and Q) at a color subcarrier frequency fsc. Composite signal with signal C: S=Y+C=Y+U&(2πfsc t)+Va(
2rfsc t).

Here, if the frame frequency fy (30Hz), the field frequency fV, and the horizontal scanning frequency fH, then fsc
=455. H=455,525 fv=455.525
f.

becomes.

Therefore, when an NTSC composite color television signal is sampled at a Q sampling frequency fs that is four times the color subcarrier frequency fsc, the sequence of the sampled signals is arranged as shown in FIG. That is, the phase of the color signal C is inverted by 180 degrees for each line, and four samples are extracted in one cycle of the color subcarrier.

In order to separate such a signal into a luminance signal Y and a color signal C,
Conventionally, a square-shaped filter as shown in FIG. 3 was used to separate the luminance signal and color signal.

In addition, the input television signal (Y-C) in Fig. 3
is the previous line signal (y
+c) in adder 2. In other words, as shown in Figure 2, the phase of the color signal is reversed by 180 degrees between the current line and the previous line, so the output of adder 2 is 2Y, and the level is reduced by half by the next attenuator 3. The attenuated luminance signal Y is separated. In addition, the input television signal (y-
After c) is inverted by the inverter 4, it is also added to the previous line signal in the adder 5, and its output is 2C
Then, the level is attenuated to 1/2 by the attenuator 6, and the color signal C is separated.

[Problem that the invention seeks to solve]

The conventional luminance signal/chrominance signal separation device as explained above uses the pixel information of the previous line on the assumption that the pixel information, which is the sampling sequence of the composite color television signal, has a strong correlation in the vertical direction. The luminance signal and chrominance signal of the current line were separated.

However, in the conventional method described above, the luminance signal and color signal are separated based on the above-mentioned assumptions, so in areas where the luminance and color of the image change rapidly, color clouding and dot interference may occur. etc., deterioration of the reproduced image occurs, and
A method of adaptively separating the luminance signal and color signal while looking at the correlation between images has been considered, but the problem has been that the configuration becomes complicated.

The present invention has been made in view of the above-mentioned problems, and uses a simple configuration to accurately separate a luminance signal and a color signal from a composite color television signal according to the correlation state of images. The purpose is to provide a signal separation device.

[Means for solving problems]

When the luminance signal color signal separation device of the present invention samples a combined color television signal and obtains a pixel information signal, an arbitrary one pixel among the pixels on one screen is set as a pixel of interest, and the focus is focused on the pixel of interest. pixel forming means for forming a plurality of pixel groups each consisting of a pixel, at least one pixel having a color signal in phase with the pixel of interest, and at least two pixels having a color signal of opposite phase to the pixel of interest; and the plurality of pixels formed. Correlation determining means for determining a pixel group having the strongest correlation between a pixel of interest and a pixel in phase with the pixel of interest among the pixels constituting each pixel group among the groups, and pixels constituting the pixel group determined by the correlation determining means. and separation means for separating the luminance signal and color signal of the pixel of interest using the information signal of the pixel of interest.

[For production]

With the above configuration, it is possible to separate the luminance signal and the color signal using the information signals of the pixels constituting the pixel group with the strongest correlation depending on the correlation state of the image.

〔Example〕

Hereinafter, the present invention will be explained based on examples.

FIG. 1 is a diagram showing a schematic configuration of a luminance signal chrominance signal separation circuit as an embodiment of the present invention.

FIG. 4 is a diagram showing a pixel block configuration for determining pixel correlation.

In FIG. 1, 7 to 12 are 2 sample period delay circuits;
13.14 is the IH-4 sample period delay circuit (however, H
is 1 horizontal line scanning period), 15 to 19 are subtractors, 20
23 are absolute value converters, 24 to 26 are 1/2 level attenuators, 27 and 28 are adders, 29 is a comparison circuit, and 30 is a switching circuit.

For example, when an NTSC composite color television signal is sampled at a sampling frequency fs that is four times the color subcarrier frequency fsc, the sampling points are as shown in FIG.

In FIG. 4, the operation of separating the luminance signal and color signal for the sample point S3 will now be described.

In FIG. 1, when an NTSC composite color television signal sampled at a sampling frequency fs that is four times the color subcarrier frequency fsc is sequentially input, the signal is transmitted to two sample period delay circuits 7 to 12; The sample point S s = shown in FIG. 4 by the IH-4 sample period delay circuit 13.14
Pixel information signals of Se are extracted simultaneously. In addition, the fourth
As for the pixel information signal of the sample point as shown in the figure, the phase of the color signal is the sample point Ss.

St, Ss, and Ss are in phase with the sample point S, and the sample point layer Ss + S4 q Ss is in reverse phase with the sample point S. As mentioned above, this is the color subcarrier frequency fsc of the NTSC system composite color television.
This is because sampling was performed at a sampling frequency fs that is four times higher than .

By the sample points S, ~S9 obtained as above, t:l
! A luminance signal and a color signal are separated for each pixel block A to D shown in FIG. The luminance signal Y and color signal C in each pixel block are pixel block A: Ya=+(2Ss+S++St),
Ca=+(2Ss-5L-82) pixel block B' Y
b=+ (2Ss+S++S< ), Cbz+(2S
s−St −84) Pixel block C: Yc”+ (,2
Ss+Sz+Ss), Cc=+(2Ss-'St
-8s) Pixel block 'D' Yd=+ (28s+8
4+Ss), Cd=+(2Ss-S4-8s; Therefore, the extracted pixel information signals S+ to S9 are sent to the subtracter 19, adder 27, 28, and ten level by the switching circuit '30 as described later. It is supplied to a separation filter constituted by attenuators 24-26.

Here, the pixel information signals 81 to 81 are applied to the separation filter as described above.
In order to determine which of S9 to supply, the block with the strongest correlation among the pixel blocks A to D is determined by the following method, and the pixel information signal of that block is selected,
The signal is supplied to the separation filter to output a luminance signal and a color signal.

That is, subtracters 15 to 18, absolute value converter 2is,
s, l = T c , l S3 Sl =='ra Note that in the above equation, when the result is large, the correlation is weak, and when the result is small, the correlation is strong. Furthermore, by using the information signals of pixels whose color signals are in phase to determine the correlation in this way, calculations become easier and the circuit configuration becomes simpler.

Then, the above calculation result is input to the comparison circuit 29, which detects the smallest value among Ta-Td,
When Ta is small, S+, Sz; when Tb is small, bl + Sa; when To is small, Sz, S
When s and Td are small, the comparison circuit 29 outputs a switching control signal to the switching circuit 30 so that 84°Ss is output from the switching circuit 30, and the output pixel information signal is the pixel information of the sample point S3. The signal is input to a separation filter based on the signal, and by performing the calculations described above, the signal is separated into a luminance signal and a chrominance signal and output.

As described above, when separating a luminance signal and a chrominance signal from a composite color television signal, it is possible to perform optimal separation according to the correlation between the luminance signal and chrominance signal on the same screen.

FIG. 5 is a diagram showing a schematic configuration of a luminance signal/chrominance signal separation circuit that also utilizes the temporal correlation of image information as another embodiment of the present invention.

In Figure 5, 30 is 525H-2 sample period 1μJ
Delay circuit, 31 is a two sample period delay circuit, 32.33
is an adder, 34.35 is a 1/2 level reducer, 36 is a subtracter, 37 is an absolute value converter, 38 is a comparison circuit, and 39 is a switching circuit. Components that are the same as in Figure 1 are given the same numbers. It is attached.

The operation of chopsticks 5 will be explained below. In FIG. 5, as in FIG. 1, an NTSC composite color television signal sampled at a sampling frequency fs that is four times the color subcarrier frequency fsc is input, and each delay circuit similar to that in FIG. 7-14 and 525H-4 sample period delay circuit 30.
The two sample period delay circuit 31 causes the sample points 81 to S shown in FIG.

and S 2' t S 3' pixel information signals are extracted simultaneously.

Then, as in FIG. 1, in order to determine the correlation between pixels on one screen, subtracters 15 to 18 and absolute value conversion circuits 20 to 23 extract each pixel of sample point S3, sample point Ss, s7゜Sa, Ss. The comparison circuit 3 compares the absolute value Ta to Td of the difference with the information signal.
7 and simultaneously two sample period delay circuit 9.10
The adder 32 adds the pixel information signals of the sample point S2 and the sample point S extracted by the sample point S2.
Sample point S2 corresponding to the sample point exactly one frame before Ss
The pixel information signals /, S, / are added by the adder 33, and the respective addition results are attenuated to half the level by the 1/2 level attenuation circuits 34 and 35, and then sent to the subtracter 3.
6, +l (Sz +Ss) −(S
The calculation result z'+Ss')'=Te is input from the absolute value converter 37 to the comparator circuit 38.

The comparison circuit 38 determines the magnitude relationship between the input calculation results Ta-Te. The calculation results T and -Td represent the correlation of pixels on one screen, and Te represents the temporal correlation of pixels. If the value is large, the correlation is weak, and if the value is small, the correlation is weak. It will be strong. Therefore, the smallest value of Ta-T8 is detected, and depending on the result, the sample point S1. The output signal based on the pixel information signal of S2°S4·+Ss l 83' is selected.

In other words, when Ta is the minimum, +(St+S*) is T
+(SI+84) when b is the minimum, +(St+Ss) when Tc is the minimum, and +(St+Ss) when Td is the minimum.
(S4+SS) outputs a switching control signal from the comparison circuit 38 to the switching circuit 39 so that when Te is the minimum, 83' is output from the switching circuit 39. Adder 28 Subtractor 19. 1/2 level attenuation circuit 25. 26 Regarding separation of luminance signal and color signal using pixel information signals of sample points in blocks A to D.
By performing the same calculation as in Fig. 1, the luminance signal,
The comparison circuit 38 determines that Te is the minimum for the pixel block E shown in FIG. S3+Ss')-C6=+(Ss
S3') is performed by the adder 28 and subtracter 19.1/
This is done by two-level attenuation circuits 25 and 26, and the luminance signal and color signal are separated.

As described above, when separating a luminance signal and a color signal from a composite color television signal according to this embodiment, not only the correlation within the current screen but also the correlation with the previous screen is considered, and the pixel with the highest correlation is It is possible to identify the block and separate the luminance signal and color signal using the pixel information signal within the pixel block.

In addition, in this embodiment, a signal sampled at a sampling frequency fs that is four times the color subcarrier frequency fsc was used as a composite color television signal of the NTSC system, but by changing the configuration of the pixel block, the PAL system can be used. This can also be applied to pond signals such as the following.

〔Effect of the invention〕

As described above, the present invention provides a luminance signal/chrominance signal separation device that can accurately separate luminance signals and chrominance signals from a composite color television signal according to the correlation state of images with a simple configuration. I can do it.

[Brief explanation of drawings]

FIG. 1 is a diagram showing a schematic configuration of a luminance signal chrominance signal separation circuit as an embodiment of the present invention. FIG. 2 is a diagram showing a series of sampled signals obtained by sampling a composite color television signal of the NTSC system using a sampling frequency fs that is four times the color subcarrier frequency fsc. FIG. 3 is a diagram showing a schematic configuration of a conventional luminance signal/chrominance signal separation comb filter. FIG. 4 is a diagram showing the relationship between the sampling points of the sampled signal in FIG. 2 and the configuration of pixel blocks. FIG. 5 is a diagram showing a schematic configuration of a luminance signal/chrominance signal separation circuit that also utilizes the temporal correlation of image information as another embodiment of the present invention. 7-12...2 sample period delay circuit 13.1
4...IH-4 sample period delay circuit 15-1
9...Subtractors 20-23...Absolute value converters 24-26...1/2 level attenuator 27.28
... Adder 29 ... Comparison circuit 30 ... Switching circuit

Claims (1)

[Claims] When sampling a composite color television signal to obtain a pixel information signal, any one pixel among the pixels on one screen is taken as the pixel of interest, and the color signal of the pixel of interest and the color signal in phase with the pixel of interest is centered around the pixel of interest. pixel forming means for forming a plurality of pixel groups each consisting of at least one pixel having a color signal of interest and at least two pixels having a color signal having a phase opposite to that of the pixel of interest, and pixels constituting each pixel group among the plurality of formed pixel groups; Correlation determining means for determining a pixel group having the strongest correlation between a pixel of interest and a pixel in phase with the pixel of interest; A luminance signal/chrominance signal separation device comprising: separation means for separating a luminance signal and a chrominance signal.